Tesi di Dottorato
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Item Feasibility of a frequency-modulated, wireless, MEMS acceleration evaluator (ALE) for the measurement of lowfrequency and low-amplitude vibrations(2014-10-28) Sabato, Alessandro; Pagnotta, Leonardo; Oliveti, Giuseppe; Fortino, Giancarlo; Feng, Maria Q.La necessità di monitorare le vibrazioni sulle strutture e su elementi meccanici assume notevole importanza. Mantenere sotto controllo strutture vetuste, infrastrutture e macchinari ricopre un ruolo strategico nella prevenzioni di situazioni che potrebbero destabilizzare, o finanche distruggere, le strutture stesse. Recenti sviluppi nei sistemi Micro Elettro Meccanici (MEMS), hanno reso gli accelerometri MEMS uno strumento attraente per il monitoraggio dello stato in cui versano diverse tipologie di strutture (SHM). Fino ad ora, la scarsa sensibilità e la bassa risoluzione dei sensori adoperati, specie alle bassissime frequenze, hanno costituito una seria limitazione per il monitoraggio di grandi strutture. Convenzionalmente, i segnali analogici in uscita dagli accelerometri MEMS sono convertiti in segnali digitali prima di essere trasmessi tramite radio-frequenza (RF). La conversione può causare perdita di accuratezza nell’analisi dei segnali caratterizzati da bassa frequenza e piccola ampiezza, che sono d’interesse nel campo dello SHM. Al fine di ovviare a tale limitazione, un nuovo sistema per la valutazione di accelerazioni (ALE) è progettato e realizzato in questo studio. ALE converte il valore di tensione in uscita dall’accelerometro MEMS in un segnale modulato in frequenza (FM) prima della radiotrasmissione. Per fare ciò, è adoperato, al posto del tradizionale Convertitore Analogico Digitale (ADC), un convertitore Voltaggio – Frequenza (V/F). Il prototipo realizzato in questo studio è formato da due schede: una trasmittente e una ricevente. La prima unità è equipaggiata con il suddetto accelerometro MEMS, un convertitore V/F e un’antenna trasmittente; la seconda, invece, per demodulare il segnale ed inviarlo ad una scheda di acquisizione dati (DAQ) collegata ad un computer, utilizza un’antenna ricevente e un convertitore Frequenza – Voltaggio (F/V). L’efficacia del prototipo realizzato, nel misurare sollecitazioni dinamiche caratterizzate da bassissime frequenze e piccole ampiezze, è valutata per dimostrare la possibilità di utilizzo di ALE nelle analisi SHM. Per fare ciò, sono state effettuate prove di laboratorio ed esperimenti su differenti strutture reali. Le prime consistono in calibrazioni statiche, studi sugli effetti che la carica residua delle batterie può avere sul comportamento delle schede, prove per valutare la distanza massima alla quale il sistema RF può trasmettere, e una serie di misure comparative con accelerometri cablati. Le seconde, invece, consistono in una serie di misurazioni effettuate su diverse tipologie di sistemi dinamici: una condotta per il trasporto di carburante (applicazioni industriali), una guglia in pietra di un edificio storico (applicazioni sismiche) e un ponte pedonale (monitoraggio di infrastrutture civili). In questo studio sono discussi i risultati raggiunti e fornite indicazioni utili per possibili futuri sviluppi del prototipo.Item High-level frameworks for the development of wireless sensor network applications(2011-11-23) Guerrieri, Antonio; Palopoli, Luigi; Fortino, GiancarloWireless Sensor Networks (WSNs) are emerging as powerful platforms for distributed embedded computing supporting a variety of high-impact appli- cations. A WSN is a group of small devices (nodes) capable to sample the real world through sensors, actuate commands through actuators, elaborate data on the node, and send messages to other nodes through radio communi- cation. However, programming WSN applications is a complex task that re- quires suitable paradigms and technologies capable of supporting the speci c characteristics of such networks which uniquely integrate distributed sensing, computation and communication. This thesis aims at providing new paradigms to support the development of WSN applications through both a domain-speci c and a general-purpose approach. In particular, this thesis provides three main contributions. The rst is related to the analysis, design and realization of a domain-speci c frame- work for heterogeneous WSNs for exible and e cient distributed sensing and actuation in buildings called Building Management Framework (BMF). BMF provides fast WSN recon guration, in-node processing algorithms, multi-hop networks, and multi-platform support, a programming abstraction to dynami- cally catch the morphology of buildings, actuators support, and an extensible human computer interface. The second contribution refers to the analysis, design and realization of a general-purpose mobile agent system for WSN, namely MAPS (Multi Agent Platform for SunSPOT). MAPS allows an e ec- tive Java-based development of agents and agent-based applications for WSNs by integrating agent oriented, event-driven and state-based programming pa- radigms. Finally, the third contribution regards the analysis, design and re- alization of a domain-speci c framework for rapid prototyping of platform independent Wireless Body Sensor Network (WBSN) applications, namely SPINE2 (signal processing in-node environment version 2). SPINE2 aims at supporting the development of WSN applications raising the level of the used programming abstractions by providing a task-oriented programming model.Item A Domain-Specific approach for Programming Wireless Body Sensor Network Systems(2011-11-23) Gravina, Raffaele; Palopoli, Luigi; Fortino, GiancarloThe progress of science and medicine during the last years has contributed to signi cantly increase the average life expectancy. The increase of elderly population will have a large impact especially on the health care system. Furthermore, especially in more developed countries, there is an always growing interest in maintaining, and improving the quality of life. Wireless Body Sensor Networks (BSNs) can contribute to improve the quality of health care services. BSNs involve wireless wearable physiological sensors applied to the human body for strictly medical and non medical purposes. They can enhance many human-centered application domains such as e-Health, sport and wellness, and even social applications such as physical/ virtual social interactions. However, there are still open issues that limit their wide di usion in real life; primarily, the programming complexity of these systems, due to lack of high-level software abstractions, and to hardware constraints of wearable devices. In contrast to low-level programming and general-purpose middleware, domain-speci c frameworks are an emerging programming paradigm designed to ful ll the lack of suitable BSN programming support. With this aim, this thesis proposes a novel domain-speci c approach for programming signal-processing intensive BSN applications. The de nition of this approach resulted in a domain-speci c programming framework named SPINE (Signal Processing in Node Environment) which is one important contribution of this thesis, along with other interesting contributions derived from enhancements and variants to the main proposal. Additionally, to provide validation and performance evaluation of the proposed approach, a number of BSN applications (including human activity monitoring, physical energy expenditure estimation, emotional stress detection, and step-counting) have been developed atop SPINE. These research prototypes showed the e ectiveness and e ciency of the proposed approach and improved their respective state-of-the-art. Finally, a Platform-Based Design (PBD) methodology, which is widely adopted for the design of traditional embedded systems, is proposed for the design of BSN systems.Item Algorithms and techniques towards the Self-Organization of Mobile Wireless Sensor, Robot and UAV Networks(2011-11-23) Costanzo, Carmelo; Viterbo, Emanuele; Palopoli, LuigiItem Autonomic computing-based wireless sensor networks(2013-11-27) Galzarano, Stefano; Fortino, Giancarlo; Liotta, Antonio; Greco, SergioWireless Sensor Networks (WSNs) have grown in popularity in the last years by proving to be a bene cial technology for a wide range of application do- mains, including but not limited to health-care, environment and infrastruc- ture monitoring, smart home automation, industrial control, intelligent agri- culture, and emergency management. However, developing applications on such systems requires many e orts due to the lack of proper software abstractions and the di culties in man- aging resource-constrained embedded environments. Moreover, these appli- cations have to meet a combination of con icting requirements. Achieving accuracy, e ciency, correctness, fault-tolerance, adaptability and reliability on WSN is a major issue because these features have to be provided beyond the design/implementation phase, notably at execution time. This thesis explores the viability and convenience of Autonomic Comput- ing in the context of WSNs by providing a novel paradigm to support the development of autonomic WSN applications as well as speci c self-adaptive protocols at networking levels. In particular, this thesis provides three main contributions. The rst is the design and realization of a novel framework for the development of e cient distributed signal processing applications on heterogeneous WSNs, called SPINE2. It provides a programming abstraction based on the task-oriented paradigm for abstracting away low-level details and has a platform-independent architecture enabling code reusability and portability, application interoperability and platform heterogeneity. The sec- ond contribution is the development of SPINE-* which is an enhancement of SPINE2 by means of an autonomic plane, a way for separating out the provision of self-* techniques from the WSN application logic. Such a separa- tion of concerns leads to an ease of deployment and run-time management of new applications. We nd that this enhancement brings not only considerable functional improvements but also measurable performance bene ts. Third, since we advocate that the agent-oriented paradigm is a well-suited approach in the context of autonomic computing, we propose MAPS, an agent-based programming framework for WSNs. Speci cally designed for supporting Java- iii based sensor platforms, MAPS allows the development of general-purpose mobile multi-agent applications by adopting a multi-plane state machine for- malism for de ning agents' behavior. Finally, the fourth contribution regards the design, analysis, and simulations of a self-adaptive AODV routing protocol enhancement, CG-AODV, and a novel contention-based MAC protocol, QL- MAC. CG-AODV adopts a \node concentration-driven gossiping" approach for limiting the ooding of control packets, whereas QL-MAC, based on a Q-learning approach, aims to nd an e cient radio wake-up/sleep scheduling strategy to reduce energy consumption on the basis of the actual network load of the neighborhood. Simulation results show that CG-AODV outper- forms AODV, whereas QL-MAC provides better performance over standard MAC protocols.